I understand your skepticism, but I believe it can't hurt. (I have jointed the NRA, by the way). Good advice on calling the congressman, I'd add senators too. And remember, they are all politicians, and they do pay attention to numbers. That petition is public record, and I'm sure its viewed by others outside the Whitehouse. In the end, will it help at all? I really don't know. That said, I don't see the down side.
====
By the way, nice AR. Didn't mean to highjack the thread; should have posted the link elsewhere.